Improving EET kinetics and energy conversion efficiency of 3D hydrophilic composite hydrogel through 2D direction biofilm growth

The limited power output of microbial fuel cells (MFCs) has impeded their widespread adoption application. Thoughtful selection of a suitable anode material not only enhances extracellular electron transfer (EET) efficiency but also stimulates microbial adhesion and proliferation. Herein, a three-dimensional conductive polymer hydrogel MXene/(polypyrrole)-(polyacrylamide) (MPP) is proposed, which can enhance the power generation performance of the bioanode by promoting the enrichment of microorganisms in the two-dimensional direction. The integration of hydrogel molecular chains within the layers of MXene effectively inhibits the self-aggregation of MXene layers, thereby facilitating the formation of ion transport channels for expedited charge storage. As a result, the maximum power density increases from 3.12 W/m3 (CF) to 6.71 W/m3 (MPP-25), the protein content of MPP-25 bioanode (59.66 +/- 2.39 mg/cm2) is 3.34 times higher than that of CF (17.85 +/- 1.53 mg/cm2), and the exchange current density value increases from 0.06 mA/cm2 (CF) to 0.26 mA/cm2. Conductive hydrogels prepared by MXene as a modifier are a promising bioelectrocatalyst for high-performance MFCs.